The Flow Cytometry Core will meet the special needs of the Program Project members. The availability of quality sorting and analysis capabilities is essential for the success of the research efforts proposed in this Program Project Grant. All the program members will be active users of both the MoFlo cell sorting and LSR fluorescence analyzer in the studies dealing from: sorting of small numbers of cells based on either cell surface or transduced gene markers; and multiparameter analyses to detect biochemical and biological changes in rare populations of lymphocytes as well as whole populations transduced with various genes. In many cases, the studies proposed in the individual programs will require triple or even quadruple staining combined with state of the art cell sorting for cell surface and/or intracellular proteins. Thus, the FIRST SPECIFIC AIM of this Core is to provide access to a newly purchased high-speed cell sorter, MoFlo. The SECOND SPECIFIC AIM of this core is to provide access to the flow analyzers including the multiparameter LSR.